high8.3

CVE-2026-30948

Parse Server vulnerable to stored cross-site scripting (XSS) via SVG file upload

Impact

### Impact A stored cross-site scripting (XSS) vulnerability allows any authenticated user to upload an SVG file containing JavaScript. The file is served inline with `Content-Type: image/svg+xml` and without protective headers, causing the browser to execute embedded scripts in the Parse Server origin. This can be exploited to steal session tokens from `localStorage` and achieve account takeover. The default `fileExtensions` option blocks HTML file extensions but does not block SVG, which is a well-known XSS vector. All Parse Server deployments where file upload is enabled for authenticated users (the default) are affected. ### Patches The fix adds `svg` (case-insensitive) to the default file extension denylist. The default regex changes from `^(?![xXsS]?[hH][tT][mM][lL]?$)` to `^(?!([xXsS]?[hH][tT][mM][lL]?|[sS][vV][gG])$)`. ### Workarounds Configure the `fileExtensions` option to explicitly block SVG uploads: ```js { fileUpload: { fileExtensions: ['^(?!([xXsS]?[hH][tT][mM][lL]?|[sS][vV][gG])$)'] } } ``` ### References - GitHub security advisory: https://github.com/parse-community/parse-server/security/advisories/GHSA-hcj7-6gxh-24ww - Fix Parse Server 9: https://github.com/parse-community/parse-server/releases/tag/9.5.2-alpha.4 - Fix Parse Server 8: https://github.com/parse-community/parse-server/releases/tag/8.6.17

Affected packages

Ecosystem	Package	Affected	Fixed in
npm	`parse-server`	>= 9.0.0, < 9.5.2-alpha.4	9.5.2-alpha.4

Affected products

Vendor	Product	Affected versions
Parseplatform	Parse-Server	before 8.6.17 from 9.0.0 before 9.5.2 Version 9.5.2

Weakness classification

CWE-79